This paper deals with a universal coding problem for a certain kind of multiterminal source coding system that we call the complementary delivery coding system. In this system, messages from two correlated sources are jointly encoded, and each decoder has access to one of the two messages to enable it to reproduce the other message. Both fixed-to-fixed length and fixed-to-variable length lossless coding schemes are considered. Explicit constructions of universal codes and bounds of the error probabilities are clarified via type-theoretical and graph-theoretical analyses.

Due to the continuous growth of wireless communication technology and mobile equipment, the history management of moving object is important in a wide range of location-based applications. To process queries for history data, trajectories, we generally use trajectory-preserving index schemes based on the trajectory preservation property. This property means that a leaf node only contains segments belonging to a particular trajectory, regardless of the spatiotemporal locality of segments. The sacrifice of spatiotemporal locality, however, causes the index to increase the dead space of MBBs of non-leaf nodes and the overlap between the MBBs of nodes. Therefore, an index scheme for trajectories shows good performance with trajectory-based queries, but not with coordinate-based queries, such as range queries. We propose new index schemes that improve the performance of range queries without reducing performance with trajectory based queries.

In multiple-input multiple-output (MIMO) wireless relay networks, simultaneously using multiple relay nodes can improve the capacity of source-to-destination communications. Recent information theories have shown that passing the same message across multiple relay nodes can improve the capacity of source-to-destination communications. We have previously proposed three relay schemes that use jointly QR decomposition and the phase control matrix; computer simulations have confirmed the superiority of these schemes over conventional ones such as amplify-and-forward and zero-forcing schemes. In this paper, we analyze the capacity and achievable gains (distributed array gain, intra-node array gain and spatial multiplexing gain) of the previously proposed relay schemes (QR-P-QR, QR-P-ZF, and ZF-P-QR) and thus provide an insight into what contributes to their superiority over conventional schemes. The analyses show that the location of the relay nodes used has a significant impact on capacity. On the basis of this observation, we further propose a method that enables each relay node to individually select its relay scheme according to its channel conditions so as to maximize the capacity. A computer simulation confirms the capacity improvement achieved by the proposed selection method.

A simple and efficient semi-supervised classification method is presented. An unsupervised spectral mapping method is extended to a semi-supervised situation with multiplicative modulation of similarities between data. Our proposed algorithm is derived by linearization of this nonlinear semi-supervised mapping method. Experiments using the proposed method for some public benchmark data and color image data reveal that our method outperforms a supervised algorithm using the linear discriminant analysis and a previous semi-supervised classification method.

This paper presents a lifting wavelet coding technique with permutation and coefficient modification processes for coding the structured geometry data of 3-D polygonal mesh model. One promising method for coding 3-D geometry data is based on the structure processing of a 3-D model on a triangle lattice plane, while maintaining connectivity. In the structuring process, each vertex may be assigned to several nodes on the triangular lattice plane. One of the nodes to which a vertex is assigned is selected as a representative node and the others are called expanded nodes. Only the geometry data of the vertices at the representative nodes are required for reconstructing the 3-D model. In this paper we apply a lifting wavelet transform with a permutation process for an expanded node at an even location in each decomposition step and the neighboring representative node. This scheme arranges more representative nodes into the lower frequency band. Also many representative nodes separated from the connective expanded nodes are made to adjoin each other in lower frequency bands, and the correlation between the representative nodes will be reduced by the following decomposition process. A process is added to use the modified coefficients obtained from the coefficients of the adjacent representative nodes instead of the original coefficients in the permutation process. This has the effect of restraining increases in the decomposed coefficients with larger magnitude. Some experiments in which the proposed scheme was applied to structured geometry data of a 3-D model with complex connectivity show that the proposed scheme gives better coding performance and the reconstructed models are more faithful to the original in comparison with the usual schemes.

Though microwave emissions in association with hypervelocity impacts have been confirmed experimentally, the emission characteristics and the emission mechanism have not yet been made clear. For example, whether the emission is noise or a coherent signal is not known. In this paper, two kinds of analyses, output waveform analysis and spectral analysis, are discussed. Regarding output waveform analysis, microwave pulses are simulated on the basis of a microcrack model in consideration of discharge current, and are compared with experimental pulses in terms of the pulse shape and width. Regarding spectral analysis, the intensity and phase of waveforms are calculated in the frequency domain to examine the frequency characteristics. The spectral intensity is nearly flat and the phase has coherency. Accordingly, the microwave emission is not noise but a sequence of independent pulses.

DTW-based text-dependent speaker verification technology is an effective scheme for protecting personal information in personal electronic products from others. To enhance the performance of a DTW-based system, an impostor database covering all possible passwords is generally required for the matching scores normalization. However, it becomes impossible in our practical application scenario since users are not restricted in their choice of password. We propose a method to generate pseudo-impostor data by employing an acoustic codebook. Based on the pseudo-impostor data, two normalization algorithms are developed. Besides, a template compression approach based on the codebook is introduced. Some modifications to the conventional DTW global constraints are also made for the compressed template. Combining the normalization and template compression methods, we obtain more than 66% and 35% relative reduction in storage and EER, respectively. We expect that other DTW-based tasks may also benefit from our methods.

This paper proposes pilot-based channel quality reporting for orthogonal frequency division multiple access/time division duplex (OFDMA/TDD) systems with cochannel interference. In the proposed method, a terminal reports his channel quality in multiple subbands to base station (BS) using channel reciprocity of TDD systems. The terminal transmits uplink pilot signals in the subbands with different transmit power which is inversely proportional to the subband-based interference power. The BS can obtain knowledge of the terminal's received signal-to-interference-plus-noise power ratio on subband basis, measuring the pilot signal power. In performance evaluation, accuracy of channel quality reporting and amount of uplink signalling are examined. From numerical results, it is found that the proposed method becomes effective as the number of subbands and terminals for channel quality reporting increases.

This paper proposes a new method for realizing the web page recommendation system by sharing users' web browse history on an anonymous P2P network. Our scheme creates a user profile, a summary of the user's web browse trends, by analyzing the contents of the web pages browsed. The scheme then provides a P2P network to exchange web browse histories so as to create mutual web page recommendations. The novelty of our method lies in its P2P network formulation; it is formulated in a way so that users having similar user profiles are automatically connected, yet their user profiles are protected from being disclosed to other users. The proposed method intentionally distributes bogus user profiles on the P2P network, while not harming the efficiency of the web browse history sharing process.

In this paper, we propose a PON-based access network based on conventional TDM-PON architecture for the smooth, economical and effective transition to the future optical access network. We also propose a dynamic MAC protocol for wavelength channel and bandwidth allocation in the TDM-PON subscriber networks, which can provide enhanced network scalability and flexibility, and greater adaptability to the increasing number of subscribers in TDM-PON. In the proposed dynamic MAC protocol, several key functions are manifested, such as multiple wavelength channel utilization and dynamic allocation of multiple time-slots to a user depending on SLA between OLT and ONUs to meet QoS requirements. A dedicated control channel is used for delivering the request and status information between OLT and ONUs. We evaluate the performances of the proposed MAC protocol thru a statistical queuing analysis and numerical simulations. In addition, through simulations using various traffic models we verify the superior performance of the proposed approach by comparing it with conventional TDM-PONs.

This paper describes a technique for controlling the degree of expressivity of a desired emotional expression and/or speaking style of synthesized speech in an HMM-based speech synthesis framework. With this technique, multiple emotional expressions and speaking styles of speech are modeled in a single model by using a multiple-regression hidden semi-Markov model (MRHSMM). A set of control parameters, called the style vector, is defined, and each speech synthesis unit is modeled by using the MRHSMM, in which mean parameters of the state output and duration distributions are expressed by multiple-regression of the style vector. In the synthesis stage, the mean parameters of the synthesis units are modified by transforming an arbitrarily given style vector that corresponds to a point in a low-dimensional space, called style space, each of whose coordinates represents a certain specific speaking style or emotion of speech. The results of subjective evaluation tests show that style and its intensity can be controlled by changing the style vector.

This paper presents a partially resonant active filter based on a digital PWM control circuit with a DSP that can improve the power factor and input current harmonic distortion factor of distributed power supply systems in communications buildings. The steady-state and dynamic characteristics of this active filter are analyzed experimentally and the relationship between the control variables of digital control circuit with the DSP and performance characteristics such as regulation of the output voltage, input power factor, input current harmonic distortion factor, boundaries of stabilities and transient response are defined. Using the partially resonant circuit, the efficiency is over 91%, which is 0.9 point higher than that of non-resonant circuit and the high frequency switching noise is suppressed. Furthermore, the digital control strategy with the DSP proposed in this paper can realize the superior transient response of input current and output voltage for the step change of load, the power factor over 0.99 and total harmonic distortion factor less than 1.1%.

In this paper, CPW-fed slot antennas using loading metallic strips and a widened tuning stub (CPW-FSLW) which provides wideband operation on the flat, a Λ-shape reflector with horizontal plate that prevents the back radiation and provides the uni-directional radiation are investigated. We observe that the size and shape of the reflector have significant impact on the impedance matching and radiation patterns. By fabricating the CPW-FSLW on the Λ-shape reflector with horizontal plate structure, noticeable enhancements in both radiation pattern and bandwidth are achieved. The antennas are verified both through numerical simulations and also measurements of the experimental prototypes and these confirm the good performance antennas. It is found that the proposed antenna can deliver a measured impedance bandwidth of 64% from 1.6 to 3.1 GHz for VSWR ≤ 2. The antennas are designed to have wideband operation suitable for applications in GSM1800, GSM1900, PCS, IMT-2000 and WLAN bands.

A new type of sound source segregation method using robot-mounted microphones, which are free from strict head related transfer function (HRTF) estimation, has been proposed and successfully applied to three simultaneous speech recognition systems. The proposed segregation method is executed with sound intensity differences that are due to the particular arrangement of the four directivity microphones and the existence of a robot head acting as a sound barrier. The proposed method consists of three-layered signal processing: two-line SAFIA (binary masking based on the narrow band sound intensity comparison), two-line spectral subtraction and their integration. We performed 20 K vocabulary continuous speech recognition test in the presence of three speakers' simultaneous talk, and achieved more than 70% word error reduction compared with the case without any segregation processing.

This paper presents a miniaturized dual-mode Doherty PA module applicable for an HPSK signal and an OFDM 64-QAM signal. Dual-mode operation with identical hardware is realized by introducing a bias switching technique, which changes bias conditions of amplifiers according to transmission signals, and employing dual-mode matching circuits, which are designed based on the results of load-pull measurements using an HPSK signal and an OFDM 64-QAM signal. The Doherty PA module consists of a Doherty stage and a gain stage. Two GaAs-HBTs for a Doherty stage and one GaAs-HBT for a gain stage are integrated onto a 1 mm-square single GaAs-MMIC. In the HPSK mode, maximum output power of 26.7 dBm, power added efficiency (PAE) of 41%, and power gain of 27 dB are obtained in the condition that adjacent channel leakage power ratio (ACLR) is under -38 dBc. In the OFDM 64-QAM mode, maximum output power of 21.0 dBm, PAE of 27%, and power gain of 28 dB are obtained under EVM < 3.0%. This is the first multi-mode Doherty PA module suitable for multi peak to average power ratio (PAPR) signals.

A fully integrated 5.8 GHz ETC transceiver LSI has been developed. The transceiver consists of LNA, down-conversion MIX, ASK detector, ASK modulator, DA VCO, and ΔΣ-fractional-N PLL. The features of the transceiver are integrated matching circuitry for LNA input and for DA output, ASK modulator with VGA for local signal control to avoid local leakage and to keep suitable modulation index, and LO circuitry consisting of ΔΣ-fractional-N PLL and interference-robust ∞-shape inductor VCO to diminish magnetic coupling from any other circuitry. Use of these techniques enabled realization of the input and output VSWR of less than 1.25, modulation index of over 95%, and enough qualified TX signals. This transceiver was manufactured by 1P3M SiGe-BiCMOS process with 47 GHz cut-off frequency.

Near-field imaging has been intensively investigated to observe the shape and the physical properties of objects, aiming at wide applications in the areas of science and engineering. In this research, by using 60 GHz band waveguide-type microscopic aperture probe, the characteristics of the near-field imaging in transmission mode have been studied by simulation and experiment. The probe is made of a WR-15 rectangular waveguide with end-shielded metal plate and a 0.5 mm-diameter aperture. In the simulation, at first, the electric field distribution at the aperture, at the rear (waveguide) and the front positions (free space) are presented. Second, the transmitted electric fields are presented for three cases: (a) scanning of a dielectric slit, (b) by varying the distance between the aperture and a dielectric sample, and (c) scanning of a dielectric groove. In the experiment, the lateral resolution with a two-slit and the depth resolution with grooves having various depths in rectangular format are described and the results show both resolutions to be much shorter than the wavelength. Finally, the scanned images of the letter N punched through a dielectric material and a leaf are demonstrated.

The performance of a MIMO-OFDM system significantly depends upon the accuracy of the channel impulse response (CIR) estimates. In the presence of correlation between the CIRs of the transmit or receive antennas, it is desirable to exploit this correlation to improve the performance of CIR estimation. In this letter, we propose a low-complexity channel estimation filter composed of four concatenated one-dimensional Wiener filters which are optimized to the channel characteristics in the time and frequency domains, and the transmit and receiver antenna front ends, respectively. Finally, the performance of the proposed scheme is verified.

In orthogonal frequency-division multiplex access (OFDMA) downlink systems, the carrier-frequency offset (CFO) between the multiple transceivers introduces inter-carrier interference (ICI). In this letter, we propose an iterative precoding scheme to suppress the ICI due to CFO. This scheme is applied at the transmitter, and can jointly cancel the ICI for all the receivers. Moreover, by the studies of the convergence behavior of the iterations, a sufficient condition for the convergence is presented. The theoretical analysis and simulation results both show that this iterative scheme is equivalent to the zero-forcing (ZF) scheme in function, but with much lower complexity.

There is an increasing requirement for supporting complex multidimensional queries in Peer-to-Peer systems. In the centralized spatial database world, R-Trees and its variant structures are widely accepted due to their capabilities to manage complex multidimensional queries. In this paper, we propose a new multidimensional indexing structure for P2P systems, called Distributed Hilbert R-Trees (DHR-Trees), in which peers organize themselves into an overlay network, dynamically maintain routing tables with region information and collaboratively execute complex multidimensional queries, such as range query and k-nearest neighbors query, efficiently. DHR-Trees has similar topology to the P-Trees P2P system. The peers' routing tables are enhanced with spatial region information, which allow multidimensional query predicates to be adapted into P2P systems with minor modification. The structure design and two major multidimensional query algorithms are presented. Our experimental results demonstrate that it performs well on range queries and k-nearest neighbors queries with multidimensional data set.